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Prostate-Specific Antigen (PSA) in Serum or Plasma by Immunoassay

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of prostate-specific antigen, a protein produced by both healthy and cancerous prostate cells, in your blood.

Quick summary

["PSA helps assess prostate health and guide decisions about further testing or treatment."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
59221-2
Short code
PSA Plr-mCnc
Synonyms
PSA Plr-mCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Ref low
0
Ref high
4
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84153
SNOMED
39392002
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors may order PSA tests to monitor prostate health, especially in men at higher risk of prostate cancer. It can also help diagnose or track conditions like benign prostatic hyperplasia (BPH) or prostate inflammation.

What to Expect Before the Test

No special preparation is needed, but you may be asked to avoid ejaculation for 2–4 days before testing to get a more accurate result. Avoid heavy exercise or strenuous activity on the day of the test.

What the Test Involves

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab for analysis using an immunoassay method to detect PSA levels.

Possible Results and Interpretation

Results are reported in nanograms per milliliter (ng/mL). While reference ranges vary by lab, higher levels may signal prostate issues, including cancer, but they can also be influenced by factors like age, recent ejaculation, or prostate conditions.

Reference range

Normal: <4.0 ng/mLN/A

Specimen: fluid

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated PSA levels can indicate prostate cancer, but they can also result from benign conditions like inflammation, infection, or an enlarged prostate. A single elevated result doesn’t confirm cancer—additional testing, like a biopsy, may be needed for diagnosis.

Short name

PSA Level

Frequently asked questions

What causes PSA levels to change?
PSA levels can fluctuate due to factors like recent ejaculation, prostate surgery, radiation therapy, or certain medications. Age is also a factor, as PSA levels naturally rise with time.
How often should I get this test?
The frequency depends on your risk factors, age, and doctor’s recommendation. Routine PSA screening is not recommended for all men, but your healthcare provider will guide you based on your individual health.
Can diet or supplements affect PSA levels?
Some studies suggest certain foods or supplements (like zinc or selenium) may influence PSA levels, but evidence is mixed. Always discuss potential supplements with your doctor before use.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy